<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>box-shadow 盒子阴影</title>
    <style>
        div {
            width: 400px;
            height: 400px;
            background-color: orange;
            font-size: 30px;
            margin: 200px  auto;
            /* box-shadow: 10px 10px blue; */
            /* box-shadow: 10px 10px 10px 20px  blue  inset; */
            position: relative;
            top: 0;
            left: 0;
            transition: 0.5s all;
            opacity: 0.5;
        }
        .box1:hover{
            box-shadow: 0px 0px  20px  blue;
            top: -5px;
            left: -5px;
        }
    </style>
</head>
<body>
    <div class="box1">你好哇</div>
</body>
</html>